Sulfite ester synthetic lubricants



United States PatentCY 2,819,211 SULFITE ESTER SYNTHETIC LUBRIQANTS Louis A. Mikeska and Jeffrey H. Bartlett, Westfield, Charles E. Thompson,'Mountainside, ,and Arnold J. Morway, Rahway, N. .1., assignorsto, Esso Research and Engineering Company, a corporatiomof Delaware No Drawing. App ication February ';2;7,i1953 Serial No. 339,491.

In recent efforts to obtain:supfilior lubricatingcompositions which have unusual and specificproperties, there have been cleveloped ,entirely; new synthetic materials ;w-ith lubricating properties,,In general these new,synthetic,- lubricants; are. characterized by viscosity properties that are outstandingat both low and hightemperaturesy-es PEClfillYqWhClhgOHlPfilifid to mineral. oils. These outstancl-t ing-- ,low and,;high temperature properties are especially desirable for-use in equipment designed to operate over a greau-temperaturedifferential, such as jet engines; or turr bines; for aircraftuse, internal combustion reciprocating cating film. It has been foundthata lubricant that is engines for aircraftand; the like.

It hasbeen -founi-that synthetic lubricants mayme desirablelfor'the lubrication, of standard automotive engines 5 In addition to the versatility of their viscosity-temperature;

relationships-some types of the lsyntheticxlubricants; invest-igated t haveanothenadvantage in thatrtheir useflhas 1 been found ,to resultin very lowrates of combustion chamber depositfcrmation,particularly when they are. usedafor long. periods of time. v,Lowrates .of formation,r

of combustionv chamber deposits result in a more efiicicnt utilization-of fuel, ,less; increasetin the octane; requirementofauengine,,lesspre-ignition tendency,. a nd aQgen eral oyeralltimprovement .in ,enginegoperation These lubricants-may also serve to reduce or remove combustion, chambendepositsfrorn an engine already containingsuchr epo its-1n;

The ,xpresenttinyention relates to a new; type of syntheti lubricatingcompositiomM/hich comprises thensulfiteiester of organiczcompoundslthat contain at least one hydroxyln groupsthats'is alcoholic in nature, that :is, which givesthew characteristic reactions of an alcoholichydroxyl group; A genericeformulafor the compounds "of invention-may be written as follows: 1

s H o In the formulaAnnd Brepresent the organic compound containing at least-lone free hydroxyl group that; is aloeit possible to prepare a wide range of lubr cants.

holiein nature,, less thehydroxyl group; that is, to,say, ,it is the radical derived from such compound. I

These new..esters rrlay.v be readily, prepared by treating.

the appropriate organic compound, with thionyllchlorlidea 5 as such,,or in the presence of a tertiary amine such, as dimethyl aniline, or pyridine. The; reaction maybe 11; lustratedby the following equation in which the organi e hydroigyl containing compound, is alcohol;

2,819,21 l PatentedzJam-zil, r1958 Thus it is possible, by proper reaction controlato use two different organic hydr-oxyl containing; compounds to fully esterify the sulfurous compound, andA-Land .B ofathe type formula may be alike or differentlt ispalso possible to treat a mixture of alcohols withmthe 8961 to, produce mixed esters. 1

For use in reciprocating engines, particularly Ias a lubricant for automotive engines, a, lubricatingtcomposition must meet several requirementsgln ordersto form an effective lubricating film and to maintain that film at low and high temperatures it must have; certain. viscositycharacteristics. At low temperatures the lubricant must be sufliciently rlabile to flowithrough;the circulatory system of the equipment-andallow movement of lubricated surfaces without an unduezpowerarequirement. In general, a lubricant should have. an ASTM pour point below about +35 P. so that it will have-.sufiicient'loW temperature lability to make it satisfactory in theselrespeetsla-At high temperatures a lubricant must,have sufiicientv fbody or thickness to furnish and maintain a-satisfactory lubribricant loss due to volatility and general molecular disintegration, and to insure againstflexplqs iouihazards at higher temperatures sometimes encountercdg a;lubricating composition should have a flash pointin excess-of about 300 F. These requisitesuarerinh re. in the term lubricating compositions, as usedqimthi specification, and the sulfite esters of this inventiongare limited to those within these operable ranges-. wThe preferred materials, as contemplated herein andaasdescribed in the preferred embodiment hereof, willhavean ASTM pour ,point below about 15 F., a flash pointuabovevabout 375: F., and will have a viscosity within the-rangeof 236 to 13 centistokes or 35 to:.=l:-Saybolt- 'seconds, Universal, at 210 F.

In general it has been foundthat-" theifabove listed properties area function botlmof molecularustructure and of molecular weight." This,factl makesl;itpossible, within certain limits, to prepare compositionshavingsimilar low and high temperature propertiesina variety of ways and also enables the manufacturento -tailor a composition to fit a certain s'et of specifications within rather general,limitsmrilihe.largegnumben of organic materials containing alcoholic hyd-ronyl-groups available for preparing the compositions of this'invention makes These organic hydroxy compoundsnmay-qcontain as many as 60 carbon-atoms lt i'sgessential,fhowever, that the total number of carboneatoms; in the-average sulfite ester molecule be betWeenFabOut-ZO to about 120, with from 25 to total, arbomatomsjbeing iespecially pre- The materials used to prepare these esters, that is, organic hydroxy compounds containing at least one free hydroxyl group which is alcoholic in character, may be selected from the following partial list. Others may, of course, be used. i

I. Unsubstituted alcohols A. Monohydrlc 1. Aliphatic Methyl alcohol ((2) Ethyl alcohol (0) Propylulcohol (d) Isopropyl alcohol (0) n-Butyl alcohol (I) Iso-butyl alcohol (g) Sec.-butylaleohol (II) Tert.-hutyl alcohol (1') n-Amyl alcohol (j) Lso-omyl alcohol (k) n-Hexyi alcohol (I) Iso-hexyl alcohol (1n) 2-ethyl-i-butanol (n) Zethyl-l-hexanol (o) Octyl alcohol (1 Isooctyl alcohol (q) 2-octanol (r) lso-nonylulcohol (a) Decyl alcohol (t) Lauryl alcohol on 'Ietradecyl alcohol (0) Pentadecyl alcohol (w) Octadecyl alcohol (I) Allyl alcohol (I!) Crotyl alcohol (7.) Oleyl alcohol (no) The terpineols (bbl C3 to C20 0x0 alcohols (cc) Alcohols derived from the "Synol" process (dd) Alcohols derived from the oxidation of petroleum fractions (ea) Alcohols derived from Gucrberts reaction (ff) Alcohols derived from the hydration oi olefins (rm) Alcohols derived via the "Oxyl" synthesis (hhl Mixtures of the above 2. Aromatic (a) Benzyl alcohol (bl Phencthyl alcohol (cl ll-phenyl i-propanol (ti) a-Naphthyl carhinol (e) Cinnnmylnlcohol (I) Diphenyl carhinol 5g) Furiuryl alcohol h) Cumic alcohol (i) Vnnillyl alcohol ljl Plperonylalcohol B. Polvhydric 1. Glycols (a) Ethylene glycol (b) 1.2-p1'opanodlol 1.3-propanedlol 1.3-hutnnedioi (e) 1,4-butanedlol LS-pcntnnodlol The vari us polyalkylene glycols e. g. 1. Polycihylcne glycois (a) Dlcthylene glycol (b) 'Triethylene glycol (c) 'Ietroethylene glycol 2. Polypropylene glycols (a) Dipropylene glycol (b) 'lripropylene glycol (h) 1.2-cyclohexanediol (i) Dccanedlol-l,l0 2. Other polyhydric alcohols (a) Glycerol (b) Z-hydroxymethyl-2-methyl propanediol-1,3 (c) Pcntacrythrltol (d) Sorbltol (a) Dlpentaerytbritol (I) Dulcltol (a) 'Irimethylol propane (It) 'Ietrumethyiol cyclohexanol (i) Benzotrlmethylol II. Substituted alcohols A. Monohydric 1. All hntic (a Halogennted alcohols l. Ethylene ohlorohydrin 2. 'Irifluoro ethanol 3. Propylene chlorohydrln 4. The various chloro-substltuted monoethers oi polyalkylcne glycols (b) Ethnnolamlne (c) 2-amino gropanol (d) 2-nltroet cool (e) 2-Nitropropnnol (f) 2-nltrobutanol (a) The vari us glycol monosters, e. g. 1. Ethylene glycol monoacctate 2. Propylene glycol monobutyrate 3. Butylene glycol monolnurate 4. Polyethylene glycol mouoestera 5. Polypropylene glycol monoesters 8. Polybutylene glycol monoesters The various glycol monoethers, e. g.

. Ethylene glycol mono-methyl ether Propylene glycol mono-butyl ether Butylene glycol mono-lauryl ether Polyethylene glycol mono-others Polypropylene glycol mono-ether! 6. Polybutylene glycol mono-ether:

popular-- 7. Polytrirnethylene glycol mono-ethers (i) The various glycol mono-lormnls, e. g. the mixed formula of glycols and alcohols (j) Hydroxy Alkyl cyanides 1. Ethylene cyanohydrin 2. a-Hydroxy lsobutyronltrlle (k) Ethanol morpholine 2. Aromatic (a) p-Mcthoxy benzyl alcohol ([2) The various chlorobenzyl alcohols (c) The various nltrobenzyl alcohols (d) 2-anilino ethanol B. Polyhydric 1. Glycols (a) Halogenatcd lycols. e. g.

1. S-chloro-l,2-propanedlol 2. 2-chloro-i,3-propanediol (b) Nitroglycols, e. g.

1. 2-nitrO-L3-propnnediol 2. 2-nitro-fi-methyl-propanediol'lfi 3. Trlrnethylol nitromethane (0) Amino glycols l. 2-amlno-l.3-propanedlol 2. 2-amino'2-rnethyl-1.3-propanediol 3. Dlethanol amine 4. 'lrimcthylol aminomethane C. Other hydroxy compounds 1. Ester; oi hydroxy acids (a) The various lactate esters (b) The various glycolate esters (c) The various hydroxy stearate esters 2. Carbonyl substituted alcohols (a) Hydroxy ketones, e. g.

l. Hydroxy acetone (b) Hydroxy nl lehy les, e. g.

1. a-Hydroxy adipaldehyde 2. E-Hydroxy proplonaldehyde Particularly desirable organic hydroxyl compounds for use in this invention are those highly branched chain aliphatic alcohols prepared by the 0x0 synthesis. The 0x0 synthesis may be described as being the catalytic reaction of an olefin with carbon monoxide and hydrogen. The reaction occurs at temperatures in the order of 300400 F., at pressures in the range of about 1000 to 3000 p. s. i., in the presence of a suitable catalyst, ordinarily a heavy metal salt such as cobalt acetate. The resulting aldehyde is subsequently hydrogenated to a primary alcohol having one more carbon atom than the original olefin. This process is described in U. S. Patent No. 2,327,066 issued to Roelen in 1943.

It has been found that particularly desirable alcohols for the formation of the formals of this invention can be prepared by the application of the 0x0 synthesis to polymers and copolymers of C and C monoolefins. These monoolefins are readily available in petroleum refinery streams, and processes for their conversion to liquid copolymers have been worked out by the art. One such process, known as U. 0. P. polymerization, consists of passing the olefin-containing stream in liquid phase in contact with an acid catalyst comprising phosphoric acid impregnated on kieselguhr. Other acidic catalysts, such as phosphoric acid or copper phosphate impregnated on silica gel, sulfuric acid, Friedel-Crafts catalysts, activated clays, silica-alumina, copper pyrophosphate, etc. may be used. Suitable conditions when employing phosphoric acid catalysts of the U. 0. P. type are temperatures of 300 F. to 500 F., pressures of 250 to 5,000 p. s. i. and feed stocks comprising refinery streams containing propylene and mixed butylenes. Suitable feed stocks, for example, may contain from 15 to 60 mol percent propylene, from 0.5 to 15 mol percent butylenes, and from 0.1 to 10 mol percent isobutylcne, the remaining being saturated hydrocarbons. Other suitable feed stocks are the dimer and trimer of isobutylene.

The preferred Oxo alcohols employed in forming the sulfites of this invention are those having from 8 to 20 carbon atoms derived from olefin copolymers having from 7 to 19 carbon atoms. In preparing these Oxo alcohols the desired olefin fraction is segregated from the crude olefin polymer product by fractionation.

The following table, for example, shows the structure and percent composition of C Oxo alcohols prepared from a C olefin stream which had been fractionated from the products obtained by the phosphoric acid polymerization of refinery gas streams containing propylene and mixed nand isobutylenes.

It will be noted that Oxo alcohols derived from the olefins produced by C -C polymerization are mostly methyl substituted.

Of the great number of organic hydroxyl containing compounds that are operable for preparing the sulfite esters of this invention it has been found that best overall results are obtained if the branched chain alcohols, such as the Oxo alcohols, are first condensed with anappropriate amount of alkylene oxide, such as propylene oxide or ethylene oxide, to form esters of polyalkylene glycols. The viscosity of the finaljproducts will increase with an increase in the amount of alkylene oxide condensed with the alcohol. The viscosityof the final prodduct can thus be adjusted to any desired level. If desired, the alcohols used may contain sulfur :or otherelements in addition to carbon, hydrogen and oxygen.

The invention will be more fully explained by reference to the following illustrative examples.

EXAMPLE 1 A 5 liter -4 necked flask equipped with a stirrer, condenser, thermometer and dropping funnel was charged with 300 2 g. (19 moles) of C Oxo alcohol (derived from tripropylene). To this was added 1071 g. (9 moles) of SOC1 during 35 minutes at 25 C. to 45 C. Heat was then applied and the temperature raised to 100C. during 1 hour. The source of heat was then removed and the product was blown with N to remove .the trace of HCl. Yield of crude sulfite ester=3380 g.

Purification of the sulfite was carried out by first washing it with 5% Na CO solution followed by three water washes, all at room temperature. After drying with Na SO the sulfite was distilled in a short path still under reduced pressure. The distillate between 122143 C. at 0.1 mm. pressure which mounted to 84% of the charge had the folio-wing analysis and inspection:

Percent sulfur 8.54 Acid No ceq./gm 0.0003 Ester No ceq./gm 0.524 Saybolt visc. at 100 :F 50.4 Saybolt visc. at 210" F 33.5 Viscosity index 103 Flash point F 360 Pour point, below ...'..F. -75

*EXAMPIZEQ This preparationwas carried out'in a'sirriilar manner tothatfor the C lOxo sulfide. :Itwas likewise distilled under "reduced pressure in 'a short path still and'most of the "distillate wascollected at 1-80-1'8-'5 C. 'at 0il 5 mm.

which 'has the 'f-ollowing analysis 'and 'inspection:

EXAMPLE .3

C .Oxo alcohol was :condensed with ,an.avera'ge of 3.2 moles of ethylene oxide. This alcohol was .-then converted into a sulfurous acid ester as follows:

One mole of the-alcohol was-treated with /2 mole of thionyl chloride by adding the latter to the former drop by drop with rapid stirring. 'lDuring -the addition of the thionyl chloride, the temperature was kept at 30 C. and on completion of theaddition the mixture was stirred at room temperature for 2 additional hours. The temperature was then raised to 130 C. for 1 hour. Nitrogen was blown through the reaction mixturethroughout the treatment.

On completion of the-reaction, the'product' was transferred into a Claisen flask and 'toppedto 250 C. metal bath temperature under '1 mm. pressure. Only a few drops of distillate were obtained which were discarded. The undistilled residue consisted of a straw-colored viscous oil showing the following properties:

.fSaybolt vis. .at .F 207.9 Saybolt vis. at 210 F .5l.5 Viscosity index 137 Flash point F 450 EXAMPLE 4 In this case C :Oxo alcohol was condensed with an average of 68 moles of ethylene oxide. The ether of polyethylene glycol thus obtained had the following properties:

Saybolt vis. at 100 F ..154.0 Saybolt vis. at 210 F 46.0 Viscosity in 136 This ether was then condensed with thionyl chloride as described in Example 1. The resulting oil consisted In a manner similarto that described above, thionyl chloride was condensed with isodecyl lactate. The resulting product was a straw-colored oil having the following characteristics:

Saybolt vis. at 100 F 121.1 Saybolt vis. at 210 F 40.4 Viscosity index 72.5 Flash point 'F- 425 Pour point F-u" -50 The synthetic oils described above are compatible with a great number of additive agents commonly used to improve specific properties of lubricating oils. For instance, these new oils may be blended with detergent additives, pour point depressors, oxidation inhibitors, viscosity index improvers, and the like. They may be used to enhance the performance of mineral lubricating oils by blending therewith in any proportion.

It has also been found that the sulfites of this invention may be used to prepare lubricating grease compositions which have excellent'properties at temperature extremes and are useful in conditions calling for high extreme pressure resistance. It has also been found that when the sulfites are employed as a base oil for grease compositions, the purification of the crude ester will be unnecessary if an excess of free alkali isused in the grease formulation. The presence of the free alkali neutralizes the acid impurity and also acts as a butter to keep the product neutral.

The following examples illustrate this concept of the invention.

EXAMPLE 6 Preparation of greases FORMULATION Ingredients: Weight percent Complex lithium soap (lithium soap of hydrogenated fish oil acids and crotonic acid, coneutralized in 1:1 mol ratio) 15.0 Phenyl alpha naphthylamine 1.0 C Oxo sulfi 84.0

PREPARATION Prepared by mixing dry pro-formed soap containing 1.0% excess lithium carbonate or hydroxide and sulfite together and heating to 480 F. Added phenyl alpha naphthylamine and cooled the fluid mass rapidly in thin layers.

Penetrations, 77 F., rum/10:

Unworked 240. Worked (60 strokes)- 310. Worked (80,000 strokes) 275.

Dropping point, F 360.

Almen test (weights carried). 9.

EXAMPLES 8 and 9 FORMULATION Percent Weight Ingredients Lithium Stearnte 10. 00 5.00 Lithium Hydroxy Stearate 10. 00 5. 00 Phenyl alpha naphthylarnine 1.00 0. 50 C13 Oxo su te 31). 00 49. 50 Di-Z-ethylhexyl sebacates 40. 00 40. ()0

PROPERTIES Appearance A Excellent Smooth uniform product Dropping Point, "F 60 Penetrations, 77 F., rum/l0:

Unworked 245 290 Worked (60 strokes) 260 310 Worked (80,000 strokes). 305 3 10 Water solubility 1 Inso uble Almeu Test (Weights carried) 9 l 9 To reiterate briefly, the instant invention relates to a new class of synthetic lubricating compositions having outstanding properties at both low and high temperatures which comprise sulfite esters of organic hydroxyl containing compounds having at least one hydroxyl group that is alcoholic in nature. The general formula may be written wherein A and B are selected from the group consisting of organic radicals having from 2 to 60 carbon atoms, the total number of carbon atoms in the molecule being from 20 to carbon atoms. The group of compounds contemplated have viscosities at 210 F. within the range of from 2 to 60 centistokes, an ASTM pour point below about 35 F. and a flash point above about 300 F. Especially preferred are the sulfite esters of the polyether glycols prepared by reacting an alkylene oxide with an alcohol.

What is claimed is:

1. A synthetic lubricating composition having an ASTM pour point below about 35 F., a flash point above about 300 P., and a kinematic viscosity within the range of 2 to 60 centistokes, which comprises an ester of the formula wherein A and B are organic radicals derived from branched chain ether alcohols having a branched chain alkyl group of from 8 to 13 carbon atoms, and containing from 3 to 7 ethylene oxide units.

2. A synthetic lubricating composition having an ASTM pour point below about 35 F., a flash point above about 300 F., and a kinematic viscosity Within the range of 2 to 60 centistokes which comprises a blend of an ester of the formula wherein A and B are organic radicals selected from the group of C to C branched chain alkyl groups with an equal amount of di-Z-ethylhexyl sebacate.

3. A lubricating composition according to claim 2 containing combined therein a minor, but grease forming, amount of a lithium soap of a fatty acid.

4. A synthetic lubricating grease composition which comprises a blend of C to C branched chain alcohol sulfite esters with an equal portion of the C branched chain ester of sebacic acid thickened to a grease consistency with the lithium soap of fatty acids.

5. A grease composition according to claim 4 wherein the fatty acid is a mixture of stearic acid and hydroxy stearic acid.

6. A synthetic lubricant having an ASTM pour point below about -15 F., a flash point above about 375' F. and a kinematic viscosity at 210 F. within the range of 2 to 13 centistokes which comprises the sulfite ester of branched chain polyether alcohols having branched chain alkyl groups of from 8 to 13 carbon atoms and containing from 3 to 7 alkylene oxide units selected from the group of ethylene and propylene oxide units.

References Cited in the file of this patent UNITED STATES PATENTS Davis Feb. 2, 1943 Bond July 6, 1943 Knutson et al. Feb. 1, 1944 Hechenbleikner May 25, 1945 

1. A SYNTHETIC LUBRICATING COMPOSITION HAVING AN ASTM POUR POINT BELOW ABOUT 35*F., A FLASH POINT ABOVE ABOUT 300*F., AND A KINEMATIC VISCOSITY WITHIN THE RANGE OF 2 TO 60 CENTISTOKES, WHICH COMPRISES AN ESTER OF THE FORMULA 